核反应

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Operation Castle was a series of nuclear tests that the United States conducted in 1954 in the Bikini and Enewetok atolls in the Marshall Islands of the Pacific. The purpose of the tests was to validate the designs of different thermonuclear weapons.
::城堡行动是1954年美国在马绍尔群岛太平洋比基尼和埃尼威托克环礁进行的一系列核试验,目的是验证不同热核武器的设计。

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Nuclear Reactions

::核反应

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In all nuclear reactions, the total of the atomic numbers on the left side of the equation must equal the total of the atomic numbers on the right side of the equation. Furthermore, the sum of the mass numbers on the left of the equation must equal the sum of the mass numbers on the right of the equation. In addition to alpha and beta decay, there are a number of other types of nuclear reactions. Bombardment of nuclei with alpha particles or neutrons can often produce a nuclear reaction. Consider the bombardment of nitrogen-14 by an alpha particle,
::在所有核反应中,方程式左侧原子数字的总数必须与方程式右侧原子数字的总数相等。此外,方程式左侧质量数字的总数总和必须与方程式右侧质量数字的总数之和相等。除了α和β衰减外,还有其他几种核反应。用α粒子或中子轰炸核经常会产生核反应。想想用α粒子轰炸氮-14,

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$$\begin{align*}{^4_2 \text{He}}+{^{14}_{\phantom{0}7} \text{N}} \rightarrow {^1_1 \text{H}}+{^{17}_{\phantom{0}8} \text{O}}\end{align*}$$
::24HE+0714N11H+0817O

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or the bombardment of uranium-235 by a neutron.
::或用中子轰炸铀-235。

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$$\begin{align*}{^{235}_{\phantom{0}92}\text{U}}+{^1_0 n} \rightarrow {^{89}_{36} \text{Kr}} + {^{144}_{\phantom{0}56} \text{Ba}}+3 \ {^1_0 n}\end{align*}$$
::092235U+01n_3689Kr+056144BA+301n

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Large unstable nuclei often become more stable by breaking into smaller pieces. The breakup of a larger nucleus into two or more smaller nuclei is called fission .  Launch the  PLIX Interactive below to learn more about processes:
::大型不稳定核心通过破碎成小块往往变得更加稳定。 大核分裂成两个或两个以上小核被称为裂变。 启动下面的 PLIX 互动来了解更多过程 :

 

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Small nuclei often become more stable by joining together to form larger nuclei. This process is called fusion .  Launch the Smashing Atoms PLIX Interactive below to learn more about :
::小核通常通过联合形成更大的核而变得更加稳定。 这个过程被称为聚变。 启动下面的Smashing Atoms PLIX互动, 以了解更多有关 :

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Here is a reaction showing the fusion of a hydrogen-2 atom and a hydrogen-3 atom.
::这是一种反应 显示氢-2原子和氢-3原子的融合

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$$\begin{align*}{^2_1 \text{H}}+{^3_1 \text{H}} \rightarrow {^4_2 \text{He}}+{^1_0 n}\end{align*}$$
::12H+13H24HHE+01n

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The disintegration of unstable nuclei does not occur all at once. The rate of disintegration is a statistical process. The most convenient way to consider it is by a concept known as . The time required for half of the atoms in any given quantity of a radioactive substance to decay is the half-life of that element. Each particular isotope has its own half-life. For example, the half-life of radium-226 is 1600 years. That is, beginning with 1.00 gram of radium-226, it would take 1600 years for half of it to decay and leave 0.50 gram remaining. After another 1600 years, only 0.25 gram would remain. In each half-life, exactly half of the beginning amount decays.
::不稳定核的分解并非同时发生。 分解速度是一个统计过程。 最方便的考虑方法是一个称为. 的概念。 在任何一定数量的放射性物质中,半原子需要的时间是该元素的半衰期。 每种特定同位素都有自己的半衰期。 例如, -226的半衰期为1600年。 也就是说, 从1. 00克的弧度-226开始, 一半的半衰期需要1600年, 剩下的为0.50克。 再过1600年, 剩下的只有0.25克。 在每个半衰期中, 每半衰期只有0.25克, 完全一半的开始衰变。

Half-lives of Various Substances

Element	Isotope	Half-life
Hydrogen	$\begin{align*}{^3_1\text{H}}\end{align*}$	12.3 years
Carbon	$\begin{align*}{^{14}_{\phantom{0}6} \text{C}}\end{align*}$	5730 years
Polonium	$\begin{align*}{^{194}_{\phantom{0}84}\text{Po}}\end{align*}$	0.7 seconds
Uranium	$\begin{align*}{^{238}_{\phantom{0}92}\text{U}}\end{align*}$	4.5 × 10 9 years

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Example  
::示例示例示例示例

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4.00 grams of tritium (hydrogen-3) are produced in the lab. How much of it will remain after 24.6 years?
::4.00克(氢-3)在实验室生产,24.6年后将保留多少?

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24.6 years is two half-lives for hydrogen-3, so $\begin{align*}\frac{1}{4}\end{align*}$ of the original amount will remain. That would be 1.00 gram.
::24.6年是氢-3的两半衰期,所以原量的14年将保持不变,为1.00克。

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Further Reading
::继续阅读

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• Conservation of Mass and in Nuclear Reactions
  ::保护质量和核反应
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• Nuclear Fission
  ::核裂变
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• Nuclear Fusion
  ::核熔化

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Summary
::摘要

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• In all nuclear reactions, the total of the atomic numbers on the left side of the equation must equal the total of the atomic numbers on the right side of the equation.
  ::在所有核反应中,方程式左侧原子数字总数必须与方程式右侧原子数字总数相等。
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• The sum of the mass numbers on the left of the equation must equal the sum of the mass numbers on the right of the equation.
  ::方程左侧质量数的总和必须等于方程右侧质量数的总和。
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• The breakup of a larger nucleus into two or more smaller nuclei is called fission .
  ::大核分裂成两个或两个以上小核,叫做裂变。
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• The joining together of two or more smaller nuclei to form a larger one is called fusion.
  ::两个或两个以上较小的核心结合成一个更大的核心,称为聚变。
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• The time required for half of the atoms in any given quantity of a radioactive substance to decay is the half-life of that element.
  ::任何一定数量的放射性物质中一半原子腐烂所需的时间是该元素的半衰期。

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Review
::回顾

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1. The isotope $\begin{align*}^{238}_{\phantom{0}93} \text{Np}\end{align*}$ has a half-life of 2.0 days. If 4.00 grams are produced at noon on Monday, what will be the mass of neptunium remaining at noon on Tuesday of the following week?
   ::同位素 093238Np 的半衰期为 2.0 日。 如果星期一中午生产 4 克, 那么下周星期二中午剩下的质量是多少 ?
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2. Write the equation for the alpha decay of a polonium-214 nucleus. Recall from the concept “Radioactivity” that $\begin{align*}\alpha \ = \ ^{4}_{2} \text{He}\end{align*}$ .
   ::写入-214核的α衰变方程式。 从α=24HE的“放射性”概念中回顾出来。
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3. Complete the following equation: $\begin{align*}{^2_1 \text{H}}+{^2_1 \text{H}} \rightarrow {^3_1 \text{H}}+\underline{\hspace{0.5cm}}\end{align*}$
   ::完成以下方程: 12H+12H13H______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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Explore More
::探索更多

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Use this resource to answer the questions that follow.
::使用此资源回答下面的问题 。

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1. What was used as a target in the Cockcroft and Walton experiment?
   ::鸡科罗夫特和沃尔顿实验用什么作为目标?
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2. Name two famous scientists whose actual voices are heard in this video.
   ::列出两位著名的科学家,